WSS SearchScalability:Search covers a single site collection. Only SharePoint content in the site collection can be crawled. You cannot crawl databases, mail servers, application servers, or Web sites and file shares outside of the site collection. In a deployment with more than one site collection, each site collection provides search only for content on that site collection, and there is no aggregation of search results across site collections.

Content sources: One content source is automatically created for each Web application in the site collection, and no administration details are exposed to administrators.Search scopes: Search is automatically scoped to current context and limited to site and subsites, list or library, or folder. These search scopes appear in the search dropdown menu. If you are looking at a subsite, you cannot search over the entire site collection, but you can search over all of the subsites of the current site. Scope management is not exposed to administrators.Crawling: Full crawls occur automatically without scheduling and without administrator control.Error logging: Administrators can view a limited set of error message types, including:- Authorization messages.- Propagation messages.- Hardware failure and data corruption messages.IFilters: A limited set of IFilters to search content in certain formats are included with Windows SharePoint Services 3.0. Other IFilters are available by installing the Microsoft Filter Pack or through other distributorsThe search service runs on one or more servers in the farm, depending upon the servers you select during deployment and configuration. Search consists of search query and index roles. Search queries are performed using the network service account, or another account selected during installation. A separate content access account is used when crawling content sources and indexing content. A small set of administration tasks are available to site collection and farm administrators.People using a site collection type search terms into the search box, and select a search scope from the dropdown menu. Search results appear in order of relevancy. MOSS SearchHigh Level Search Concepts: Essentially, there are two main components of search: the indexing and the querying. The indexing is the process in which all documents and content are reviewed and many key items about the item (meta data) are stored. The querying is when a user wishes to search for an item. The user enters keywords or phrases and the query engine looks at the indexed content and returns items that match. The indexing process is called “crawling” and the indexed content is called “crawled content.” The querying and the query results (search results) is the end-user experience of the MOSS Search capabilities. Usually in a MOSS farm, there is one server dedicated to perform the indexing and the querying, however, these functions may be split out onto two separate servers. In Office SharePoint Server 2007, search results are delivered quickly and relevance is tuned for enterprise and line-of-business data. - Relevance is tuned for enterprise content with the best results across structured and unstructured data sources determined by a rich and broad range of factors.- Robust security, granular administrative controls comprehensive monitoring, analytics, and reporting help ensure compliance and protect intellectual property (IP).- Enterprise-grade scalability, extensibility, and manageability meet the needs of even the largest organizations. Office SharePoint Server 2007 provides out-of-the-box search for common enterprise repositories and file types as well as for people and experts. With Office SharePoint Server 2007, you can: - Search file shares, Web sites, SharePoint sites, Exchange Public Folders, and Lotus Notes databases out of the box and easily extend search to third party sources and file types.- Index, search, and intelligently display information from line-of-business applications, relational databases, and other structured content using the Business Data Catalog.- Leverage "people search" capabilities to find people not only by department or job title but also by expertise, social distance, and common interests.

Enterprise search functionality is integrated with the collaboration, portals, content management, forms and business intelligence features of SharePoint Server 2007 and can be integrated with other 2007 Office system products to help users easily find, use, and share information and increase productivity.

- Find, use and share information in the context of where you are working with the familiar tools you use every day.- Results are displayed more clearly, hits are highlighted, duplicate entries are collapsed, and synonyms are suggested.- Results are actionable and further enhanced through optional integration with tools such as real-time communications.

In Short,WSS 3.0 Search Single Site collection, automatically scoped to current site (and subsites):Only SharePoint content in the site collection can be crawled. You cannot configure Search to crawl databases, mail servers, application servers, or Web sites and file shares outside of the site collection. In a deployment with more than one site collection, each site collection provides Search only for content on that site collection, and there is no aggregation of search results across site collections.MOSS SearchMOSS uses an enhanced relevance algorithm for its search engine, and is able to crawl content from multiple sites within an enterprise, as well as non-sharepoint web sites. In short, the MOSS search engine is a powerful enterprise search engine with a relevance algorithm, while the WSS site-local search engine is actually pretty useless beyond simple "dumb keyword" search.